Phase composition and structure of boride layers grown on laboratory-cast low-chromium alloys

Abstract

Three Fe-C-Cr alloys containing up to 5.65 wt% Cr have been laboratory cast and homogenized, borided for 15 h at 850° C with a B₄C-base powder mixture and then characterized by using surface Mössbauer spectroscopy, X-ray diffraction, metallography and microhardness measurements. The boriding depth and the nature, disposition and relative amounts of the reaction products have been determined and discussed with regard to the chromium content in the alloys. The mechanical compactness and hardness of the innermost Fe₂B single-phase layers, which are quantitatively predominant in the boride coatings, have been related to the extent of crystallographic order.